The invention relates generally to an inertial land navigation system, and relates specifically to a vehicle land navigating device for measuring and updating vehicle heading by North-seeking and navigating.
It has been known in the art to provide inertial land navigators which include gimballed gyroscope suspensions and/or accelerometers.
In U. S. Pat. No. 4,321,678, the vehicle positioning apparatus includes a plurality of gimbals associated with torquers and angle-measuring devices for suspending the two-axes gyroscope, a plurality of accelerometers for assisting direction-finding thereby, and magnetic sensors. In U.S. Pat. No. 4,347,573, the land-vehicle navigation system includes three single-axis gyroscopes strapped down to the vehicle for land navigation.
In U.S. Pat. No. 4,507,737, the heading reference and land navigation system includes a two-axis gyroscope, assisted by two accelerometers, providing limited attitude in North seeking. In U.S. Pat. No. 4,512,086, the heading indicator includes a two-axis gyroscope with a gimbal support, providing limited attitude in inclination.
In U. S. Pat. No. 4,530,237, the gyroscopic navigational installation system includes two gyroscopes, one gimbal support therefor, and two accelerometers for aiding vehicle navigation. In U.S. Pat. No. 4,583,178, the vehicle strapped-down inertial system includes a pair of gyroscopes, a pair of accelerometers, and gimbals.
However, such systems are very expensive, particularly in view of such gimbals and accelerometers.